Concrete slabs are often poured directly on top of leveled soil or on top of a thermal insulator layer on the ground for a variety of building projects. Shrinkage of the concrete as well as thermal contraction and expansion often cause cracking in large slabs. The cracks that develop are aesthetically unpleasing and can also lead to safety concerns. Cracks may also allow substantial amounts of water leakage, causing property damage.
To combat cracking, large slabs of concrete often are divided into smaller sub-slabs by means of expansion joints. Most expansion joints are simply rectangular objects situated between the slabs of concrete. The deformation throughout the concrete that typically occurs will instead occur at the expansion joints and the concrete slabs will remain relatively crackless.
A variety of different types of expansion joints are available, requiring a variety of different types of installation methods. An expansion joint may be pressed into the fluid concrete after it has been poured and spread, but prior to it curing. Other times, grooves are cut on the surface of the slab by means of a saw.
Some expansion joints are embedded into concrete with metal reinforcements at the edges. The joint between the flat steel bars is cut open once the concrete has hardened and then filled with elastic material. However, this type of expansion joint requires a tedious and difficult installation process.
Wood bars are also often used to create an expansion joint. While the wood joints are initially attractive, they expand by absorbing water from the wet concrete and then contract as they dry. This process leaves a void space where the wood abuts the concrete at its side surfaces, allowing water to seep into the space to erode the joint. When these joints deteriorate, they become less aesthetically pleasing and need to be replaced. They also often come loose, leaving no expansion joint between adjacent slabs of concrete.
Hence, there is a need in the art for a convenient to use, inexpensive, durable, safe, effective, flexible and stationary expansion joint for use with concrete to replace existing expansion joints.